JPS629877A - Pneumatic tool - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention uses compressed air to move a piston forward and backward, and the tip of the piston strikes the rear end of a chisel, etc., and the chisel etc. is used to move rocks, concrete, etc. This relates to air-powered tools used for crushing, chiseling, nailing, etc.

[Conventional technology]

There are many types of reciprocating tools that use compressed air, but most of them have a free piston that also serves as a hammer, and a switching valve is used to alternately send air back and forth to make the piston reciprocate. It has become.

With this structure, as the piston moves back and forth, the cylinder or housing is inevitably subjected to a force in the opposite direction to the movement of the piston due to the action of air pressure. Therefore, the cylinder or housing is subjected to alternating forces in the front and rear directions, causing vibrations. Vibration from hand-held tools has recently become a huge problem from an occupational health perspective, and various countermeasures have been proposed. There are things that I have suppressed.

That is, the invention described in Japanese Patent Publication No. 58-19434 uses a stepped piston having a large diameter part and a small diameter part,
The large diameter part is placed on the chisel side.

A chisel bushing having the same outer diameter as the large diameter portion of the piston is fitted in the piston so that it can move forward and backward in the axial direction. With this structure, supply pressure is always applied to the small diameter portion of the piston, and air is intermittently supplied to the large diameter portion of the piston (by switching pulp, etc.). When pressure is applied to the large diameter portion due to the difference in area, the piston will retreat. When the pressure is released, the piston moves forward (impact) and reciprocates. Here, when pressure is applied to the larger diameter side of the piston, axial force is applied to the piston, chisel, and chisel bush. Since the latter force is supported by the object being struck, no force acts on the housing. (Pressures acting in the radial direction cancel each other out.) Also, the pressure applied to the small diameter section acts on the piston and housing, but this pressure does not cause vibration because there is almost no fluctuation.

[Problem that the invention seeks to solve]

If the structure described in Japanese Patent Publication No. 5B-19434 is implemented, a reciprocating tool with extremely low vibration can be realized.

However, this structure has major practical problems. In other words, with this structure, there is always a force applied to the housing in the rear chamber of the piston, and this force acts in the opposite direction to the object being struck.In order to continue the work, it is necessary to always hold down the housing with a force that exceeds this force. There is. This force is approximately equal to the product of the cross-sectional area of the small diameter part and the air pressure.
However, if you try to secure enough impact energy, the lifting force will become stronger in proportion to this, which puts a limit on the size of tools to which this structure can be applied.

The purpose of the invention is to solve these problems.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention connects an air chamber having a large capacity and communicating with a compressed air source through a valve to an intermediate chamber of a cylinder fitted with a chisel at the front end. A small diameter portion at the rear of the main piston fitted in the cylinder is inserted into the intermediate chamber so that it can move forward and backward, and a sub-piston is fitted into the rear of the intermediate chamber inside the cylinder so that it can move forward and backward. a communication path which is inserted into the cylinder so that it can move forward and backward, communicates the intermediate chamber with the front chamber of the cylinder and applies air pressure to the front end of the main piston; and when the main piston moves backward by a certain stroke, the front chamber communicates with the exhaust port;
A valve mechanism is constructed between the main piston, the sub-piston, and the cylinder to isolate the intermediate chamber from the air chamber and communicate the intermediate chamber to the exhaust port when the sub-piston retreats by a certain stroke.

〔Example〕

FIG. 1 shows an embodiment showing the basic structure of the present invention. Reference numeral 1 denotes a cylinder in which a chisel 2 is fitted in the front end, and a main piston 3 and a sub-piston 4 are fitted inside the cylinder, and a main piston 3 and a sub-piston 4 are fitted between the front ends of the sub-piston 4. An intermediate chamber 6 is provided in the intermediate chamber 6, and the intermediate chamber 6 is closed by interposing a spring 7 or by providing a thin protrusion 8 at the front end of the sub-piston 4 or at the rear end of the main piston 3 as shown by the chain line. 6 should not be reduced beyond a certain level.

It is fitted in the chamber 11 so that it can move forward and backward.

Reference numeral 13 denotes a supply port provided in the air chamber 11, which communicates with a compressed air source such as a compressor via a valve (not shown).

Further, when each piston 3.4 is in the forward position, the intermediate chamber 6 is connected to the front chamber 1 in the cylinder 1 through a communication passage 14.15.
6 and the air chamber 11.

Further, inside the cylinder 1, there is a rear chamber 17 behind the large diameter portion of the front end of the main piston 3, and a rear chamber 18 behind the large diameter portion of the front end of the sub-piston 4, which are isolated from the air chamber 11. .

Furthermore, the cylinder 1 has an exhaust port 21.22 that always opens the front and rear chambers 17.18 to the atmosphere, and an exhaust port 2 that opens the front chamber 16 to the atmosphere when the main piston 3 is in the retracted position.
3 and an exhaust port 24 for opening the intermediate chamber 6 to the atmosphere when the sub-piston 4 retreats.

To explain the operation of the first embodiment, a valve (not shown) is opened and pressurized air is supplied from the supply port 13 to the air chamber 11. The pressure air applied to the rear end surface and simultaneously flowing into the intermediate chamber 6 via the communication passage 15 applies pressure to the front part of the sub-piston 4, so the sub-piston 4 begins to retreat due to the difference in area.

Furthermore, pressure is applied to the front and back of the main piston 3 through the communication passage 14, and the main piston 3 also moves backward due to the difference in area.

As the main piston 3 retreats, the small diameter portion 5 opens the communication path 1.
4.15, and intermediate chamber 6 from air chamber 11,
Next, the exhaust port 23 communicates with the front chamber 16 and the front chamber 16
is opened to the atmosphere.

In addition, the intermediate chamber 6 is also closed to the exhaust port 24 due to the retreat of the sub-piston.
Since the main piston 3 is connected to the atmosphere and exposed to the atmosphere, the pressure at the front and rear of the main piston 3 drops to atmospheric pressure, and there is no external force, but the main piston 3 continues to move backward due to its inertia.

On the other hand, since the pressurized air acting on the front end of the sub-piston 4 is exhausted, only the air pressure applied to the rear end fleas of the small diameter portion 12 acts thereon. As a result, a brake is applied to the backward motion of the sub-piston 4, and at the same time it stops, it reverses itself and starts moving forward, and the main piston 3, which is retreating due to inertia, and the buffer spring 7, protrusion 8, etc., maintain an appropriate distance. That is, it makes contact with the intermediate chamber 6 in its presence and pushes it back forward.

In this way, when the main piston 3 and sub-piston 4 reach the predetermined positions, the intermediate chamber 6 communicates with the air chamber 11 again, and air pressure is applied to the rear end of the small diameter portion 5 of the main piston 3, accelerating the forward movement of the main piston 3. and hit Chisel 2's head.

After that, it returns to the initial state and repeats the same operation as before.

The embodiment shown in FIG. 2 has the same basic operation as the embodiment shown in FIG. 1, but has a shorter overall length.

That is, a concave hole 31 of a required depth is provided from the rear end of the main piston 3, and a small diameter portion 3 formed at the front part of the sub-piston 4 is formed.
2 is inserted into the recessed hole 31 so as to be freely advanced and retracted, a recessed hole 33 of a required depth is provided from the rear end of the sub-piston 4, and the piston 34 is fixed to the rear part of the cylinder 1 in this recessed hole 33 and slides therein. The cylinder 34 is fitted freely, and the rear end of the cylinder 34 is communicated with the air chamber 11.

Further, a slidable sleeve 35 is interposed between the cylinder 1, the chisel 2, the main piston 3, and the sub-piston 4, and the front and rear circumferential grooves 38.
A groove 40 is provided on the inner periphery of the sleeve 35, and two communication holes 41.42 are provided on the inner periphery of the sleeve 35. When the main piston 3 moves forward, the communication path 14.
4.15 is configured to communicate with the intermediate chamber 6.

Furthermore, the sleeve 35 has a plurality of communication holes 44, 45, 4.
6 are provided, and these are connected to the front chamber 16, the communication passage 14, and the exhaust port 2.
3.24, and the main piston 3 is connected to the exhaust port 23 through the communication hole 45 through the front part of the concave hole 31 when the main piston 3 retreats.
A communication hole 47 is provided to communicate with the.

In addition, a compression spring 50 and a cushioning material 56 such as a rubber ring are provided in the bottom of the concave hole 31, and a compression spring is also provided between the ring fixed to the outer periphery of the sleeve 35 near the rear and the stepped portion at the rear of the inner periphery of the cylinder 1. 52, and a plurality of rubber rings 53 are installed between the stepped portion on the front outer periphery of the sleeve 35 and the protrusion on the front inner periphery of the cylinder 1 as a cushioning material.

In the case of the above embodiment, the pressurized air in the air chamber 11 is
5 → Circumferential groove 39 → Communication hole 42 → Intermediate chamber 6 → Groove 40 → Communication hole 41 → Circumferential groove 38 → Communication passage 14 → Communication hole 44 → Front chamber 16. Due to the difference in area in front of main piston 3, main piston 3 retreats. At the same time, the pressurized air in the intermediate chamber 6 also applies rearward pressure to the stepped portion 55 on the outer periphery of the small diameter portion 32 of the sub-piston 4, and the pressurized air in the air chamber 11 passes through the cylinder 34 to the sub-piston. ,-J,IIRnear,%h l,,-y
Although forward pressure is applied to the z portion, since the area of the step portion 55 is larger than the cross-sectional area of the recessed hole 33, the sub-piston 4 also moves backward.

In this way, while the main piston 3 is retracting, the circumferential groove 38.
39 is blocked, then the communication holes 47 and 45 are communicated,
Further, the front end of the main piston 3 is located behind the communication hole 45, and the front chamber 16 is communicated with the exhaust hole 23 to be at atmospheric pressure.

Furthermore, the stepped portion 55 of the sub-piston 4 that is retracting is also connected to the communication hole 46.
At the rear, the retreated intermediate chamber 6 becomes atmospheric pressure.

This main piston 3 continues to retreat further due to inertia.

On the other hand, when the intermediate chamber 6 reaches atmospheric pressure, all the forward force applied from the air chamber 11 to the concave hole 33 of the sub-piston 4 becomes effective, and this applies a brake to the retreat of the sub-piston 4, causing the piston 4 to - The sub-piston 4 then stops, and after contacting the buffer material 56 in the concave hole 31 of the main piston 3 via the bi-50, both pistons 3.4 move forward together, and in the process, the intermediate piston 4. Since the chamber 6 communicates with the air chamber 11, the forward speed of the main piston 3 is further accelerated and strikes the head of the chisel 2.

After that, the above operation is repeated.

〔effect〕

This invention has a main piston and a sub-piston fitted in the cylinder as described above, and when the main piston moves forward, the main piston moves forward while being pushed by the sub-piston, and when the main piston strikes the chisel, the main piston moves forward while being pushed by the sub-piston. The sub-piston moves back due to the pressurized air flowing into the intermediate chamber, so
The small cross-sectional area portion of the main piston is made relatively large so that sufficient impact force can be exerted without sacrificing impact energy. Also, the small cross-sectional area of the sub-piston significantly reduces the opposing force generated in the hollow air chamber. Therefore, sufficient low vibration and low reaction force can be obtained for medium-sized and large-sized pneumatic tools.

[Brief explanation of drawings]

FIGS. 1 and 2 are longitudinal sectional front views showing each embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Cylinder, 2...Chisel, 3...Main piston, 4...Sub-piston, 5...Small diameter part, 6...
...Middle chamber, 11...Air chamber, 21...Exhaust port.

Claims (1)

[Claims] An air chamber having a large capacity and communicating with a compressed air source via a valve is connected to the intermediate chamber of the cylinder fitted with a chisel at the front end.
A small cross-sectional area part at the rear of the main piston fitted in the front part of the cylinder is fitted into the intermediate chamber so as to be able to move forward and backward, and a sub-piston is fitted into the rear of the intermediate chamber of the cylinder so that it can move forward and backward. A communication path is provided in which the cross-sectional area portion is inserted into the air chamber so that it can move forward and backward, and the intermediate chamber and the front chamber of the cylinder are communicated with each other to apply air pressure to the front end of the main piston, and the front chamber is opened when the main piston moves backward by a certain stroke. A pneumatic tool comprising a valve mechanism between the main piston, the sub-piston, and the cylinder that communicates with the exhaust port, isolates the intermediate chamber from the air chamber, and communicates the intermediate chamber with the exhaust port when the sub-piston retreats by a certain stroke.